import java.util.Scanner;

//数字统计
public class quetion2 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int l = in.nextInt();
        int r = in.nextInt();
        int ret = 0;
        for(int i = l; i <= r; i++) {
            int tmp = i;
            while(tmp != 0) {
                if(tmp % 10 == 2) {
                    ret++;
                }
                tmp /= 10;
            }
        }
        System.out.println(ret);
    }
}
